Method of constructing the impervious element of earth dams



I Jan. 9,'1923. 1,441,308.- C. 0. TAPPAN. Y

METHOD OF CONSTRUCTING THE IMPERVIOUS ELEMENT 0F EARTH DAMS.

' FILED JAN- 10, I922- 2 SHEETS-SHEET l.

(301121.55 OJXPPAN. INVENTOR.

96M ATTORNEYS. I

. C. 0. TAPPAN. METHOD OF'CONSTRUCTING THE IMPERVIOUS ELEMENT 0F EARTH DAMS.

2 SHEETS-SHEET 2 CHARLES OJPIPPAM INVENTOR BY 6 i ATTORNEYS:

Patented Jan. 9, 1923,

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g Q gF iii 'GHABLES O. TAPBAN 0F NEW YORK, N. Y.

Application filed January '10, 1922. Serial No. 528,214;

To all whom itmay concern:

Beit known that 1, CHARLES O. TAPPAN, a citizen of'the United States, a resident of New York, in the county or" New York and State of New York, have invented certain new and useful Improved Methods of Construc'ting the Impervious Element of Earth Dams, of which the following'is a specifica tion.

My invention relates to an improved method of constructing the impervious element of earth dams and has'forits: object to provide an improved method of construct ing the impervious element or so-called core section of earth dams used for the storage of water and comprises a method of collecting suitable impervious material, either with or without a blending of {different materials, and of placing it in the dam in such a manner as to form a homogeneous impervious mass.

Other objects of my invention will be ap parent from the following description and from the accompanying drawings of illustrative embodiments thereof, in which- Figure. 1 is a plan of an illustrative dam; Figure 2 a vertical section taken on the line 2-2 of Figure llo'oking in the direction of the arrows and showing a valley with a completed dam; I

Figure 3 a vertical section taken on the line 33 ofFigure 1 looking in the direction of the arrows andi'l'lustrating the pervious and impervious portions of the dam; Figure 4 a plan of an illustrative dam, an impounding reservoir for collecting impervious material, and of sluicing areas from which the impervious material is collected Figure 5 a plan of an illustrative dam, impounding enclosures for collecting jim ,perviious material, and of slu'icing areas from which the impervious material is oL lected and- Figure 6a vertical section taken on the line'6-6 of Figure 5 looking in the direction of the arrowsandshowingin section an impounding enclosure and sluicing area.

Similar reference characters refer to similar ,parts throughout the drawings.

A typical earth dam isillustrated' in Figures 1,2, and 3 oi the drawings. The center section 1 of the earthfi'll composing the dam (Figure 3-) is formed of impervious material and the outside sections '2 are {formed *o' f 'iperviousior semi-'pervious mate rial, the center section or core 1 constituting the watertight, cut-ofi element, vdesigned to give water tightness to the structure.

The methods adopted for constructing earth dams heretofore may beclassified in general as the dry method, the hydraulic fill method, and the semi-hydraulic method.

1. By the dry method, the pervious or semi-pervious outside sections are composed of dryearth or graveldelivered in place by scrapers, wagons, railroad cars, .or other suitable appliances, and leveled and compacted by means of drags, harrows, or similar implements. The center impervious element or core is formed of dryclay and loam deposited in layers, sprinkled and rolled with grooved rollers to compact it into a solid mass designed to serve-"as the watertight, cut-off element of the'structure. Frequently suitable impervious materials are not available at the site and must be brought from a distance at great expense, and under conditions where impervious material is available it often is found in small scat tered quantities or in such thin deposits as to make the collection of it expensive and slow.

:2. By the hydraulic fill method, where there is adjacent "the site material comprising a mixture of pervious and impervious material in such proportions as to furnish sufficient impervious material for the core byYthc use or water classification, earth dams are built by delivering the-material into the fills hydraulically, either by means of sluicing with streams of water under pressure-from deposits higher than the dam,

or elevatingthe material into place by means of hydraulic dredges. By this method ofconstruotion the mixturesof pervious and impervious material 'is delivered on to the outside pervlous or semi-pervlous sections of the dam. A pool of water is carried between the fills-so formed, into which settles by water classification in the center section forming the core, the fine elements and the impervious elements such as the clay and loam, so that-if there is a suificiency of these elements in thematerial an impervious core is formed. Heretofore it has not been possible ito build earth dams by the hydraulic fill method where the availablematerial did not contain sufficient impervious elements to form the center impervious'core.

.3. By the semi hydraulic methodqnaterial deposited. in the outer pervious sections of the dam by railroad cars or other appliances, and the inner faces of the embanlnnent so formed are sluiced with a powerful stream of waterso that the impervious elements in the [ill such asclay and loam are separated hydraul' :ally and settle in a pool, so that by water classification an impervious core is created from the material sluiced from the side fills in a manner somewhat similar to the hydraulic fill method. In practiceit often has been found that there was not suliicient impervious elements in the main fills and it also has proved diilicult to control the bound arics of the impervious core.

My improved method of constructing; the impervious core for earth dams consists of collecting the impervious material by ground-sluicing it with a stream of water from sluicing areas 5 into a reservoir site 6 such as is illustrated in Figure 4. preferably located on a small body of water as a pond, creek, brook. or stream 4:. The collected material then is conveyed into the dam between the pervious fills and preferably. aljlowed to consolidate in water as in the hydraulic fill method of construction, or conveyed first to a sump ,or open tank from which it may be pumped or otherwise conveyed into place in the dam.

Where the deposits of suitable material are located in thin layers along the slopes or hills, illustrated in Figures 5 and (3, the impervious material may be collected by ground-sluicing areas 5 with a stream of water, and conveying the impervious material and water (by flumes if required), into impounding enclosures 7 formed by brush dams S or other similar structures. The material so collected may be conveyed directly into place in the dam orlirst conveyed tosumps or open tanks 9 to which sufficient water is added so that the mixture preferably may be delivered. by pumps 10 into place between the pervious fills 2 and consolidated: under water (if desired) in accordance with the usual practice in the hydraulic fill method of construction.

The two methods may be combined in whole or in part according; to the particular conditious encountered.

c B y means oil. my improved methods of con struction. described above. Dervious material can be collected, delivered. W in the structure of the dam, and better and more cheaply consolidated than by the (3 y method used heretofore. l i hen used in, conr hination with the hydraulic fill method of construction, it is possibleby my improved methods of construction to build dams hydraulically where tron] lack of suitable impervious elements in the material available for the hydraulic fills, the use of the by .draulic method would be impossible.

When used in combination with the semiln place vious element or hy flraulic method of building dams, my improved methods of construction produce a .more homogeneous impervious core and struction to" sample the material collected,

and by blending or mixing the various materials, obtain an impervious material of the best character obtainable from the available areas. Thus different reservoirs or impounding enclosures or suitably located sumps or open tanks may be constructed adjacent areas of material varying as to imperviousness or suitability for core construction, and by blending as above described, a uniform and satisfactory impervious material is secured. Figure 5 of the drawings illustrates two such different impounding areas 7, the materials collected in which maybe blended or mixed in sump or open tank 9 in the proper proportion to use to best advantage the different materials obtained from the two separated sluicing areas5.

Many modifications of my invention will be apparent to those skilled in the art without departing therefrom or from the scope of the claims, my invention not being limited to the embodiments chosen for purposes of illustration but comprisin a. method of coni-iti-uctiiuz the impervious elements of water retaining structures by impounding in reservoirs or enclosures impervious material collected by sluicingr and then conveying the same into place between the pervious sections of the structure adapted to retain the impervious portion, either directly or by way of intermediate sunips or open tanks, and comprising when necessary or advisable the blending of material having varying characteristicsof adaptability.

What I claimand desire to secure by Letters Patent is:

1. The method of constructing the impervious element or core section of earth dams which comprises collecting in impounding enclosures byground sluicing with water,

suitable material from areas accessible to the dam s1te, blendmgthe d lil'crcnt materialcolleoted to producelthe desired core structure, and conveying; and placiuo; the blended im pervious material between the pervious outer sections of the dam so as to form a homoge neous impervious mass. l

The method of claim 1 in which the material blended in a suitably located sump or open tank to which water is added. I

3. The method of claim 1 in which thematcrial is blended in a suitably located sump or open tank to which water is added and the mixture pumped into place between the pervious outer sections.

4:. The method core section 0. earth dams ofconstructin the iinperwhich comprises collecting suitable impervious n'iaterial located in areas accessible to a reservoir site, by sluicing said material with a stream of water under pressure into said reservoir, and then conveying said collected impervious material into place between the pervious outer sections of the dam so as to form an impervious water-tight element or core section between them.

5. The process of claim t in which the collected impervious material is conveyed from the reservoir to a sump or open tank and from there conveyed into place in the dam.

6. The method of constructing the imper: vious element or core section of earth dams which comprises collecting suitable impervious material. located on slopes by sluicing same from the areas containing it with a stream of water under pressure into an impounding enclosure formed on such slopes, and then conveying the impervious material from said enclosure intoqplace between the pervious outer sections of the dam.

7. The process of claim 6 in which the col- CHARLES o. TAPPAN. 

